I plan to use more than one mail.box to speed up outgoing mails.
a) I seem to hear of advantages, but what are the disadvantages of multiple mail.box?
b) After implementing multiple mail.box, is it possible to reverse back to a single mail.box?
This can be changed back and forth. I have seen no problems with using multiple mail boxes. The only problems you might experience are if you are using monitoring software or a 3rd party app that works with your mailboxes(antivirus) that has not been upgraded to notice multiple mailboxes.